ETHICS AND INTENTIONAL CLIMATE CHANGE DALE JAMIESON University of Colorado, Boulder, CO 80309, U.S.A. Abstract. In recent years the idea of geoengineering climate has begun to attract increasing attention. Although there was some discussion of manipulating regional climates throughout the 1970s and 1980s, the discussion was largely dormant. What has reawakened the conversation is the possibility that Earth may be undergoing a greenhouse-induced global warming, and the paucity of serious measures that have been taken to prevent it. In this paper I assess the ethical acceptability of ICC, based on my impressions of the conversation that is now taking place. Rather than offering a dispassionate analysis, I argue for a point of view. I propose a set of conditions that must be satisfied for an ICC project to be morally permissible and conclude that these conditions are not now satisfied. However, research on ICC should go forward so long as certain other conditions are met. I do not intend this to be the last word on the subject, but rather the first word. My hope is that others will be stimulated to think through the ethics of ICC. 1. Intentional Climate Change (ICC) In recent years the idea of geoengineering climate has begun to attract increasing attention. In 1974, Kellogg and Schneider discussed various approaches to con- trolling climate and raised some serious questions about its advisability. Although there was some discussion of manipulating regional climates throughout the 1970s and 1980s, the discussion was largely dormant (see e.g., Glantz, 1977). What has reawakened the conversation is the possibility that Earth may be undergoing a greenhouse-induced global wanning, and the paucity of serious measures that have been taken to prevent it. The recent debate makes for strange bedfellows. Many of those who believe most strongly that climate change is occurring are reluctant to embrace geoengi- neering approaches to reversing it. This is because they believe that the 'hand of man' is implicated in most of our environmental problems and they see geoengi- neering as more of the same. Others, who are interested in exploring or developing geoengineering possibilities, are disinclined to believe that climate is changing. On their view planetary systems are relatively insensitive to human behavior and for that reason we shouldn't worry too much about the risks of geoengineering. So to simplify: some people believe that there is a problem but that geoengineering is no solution; others believe that geoengineering is a solution but that there is no problem. We might speculate that if a social consensus in favor of geoengineering emerges, it will be to attack a problem that we don't believe exists. The recent discussion has largely occurred in the corridors of scientific meetings rather than in print or in formal sessions. By the time a significant literature on its moral acceptability develops, ICC may be afait accompli. For that reason it is Climatic Change 33: 323-336, 1996. (D 1996 Kluwer Academic Publishers. Printed in the Netherlands.